Tree Coring Inquiry

FMims wrote:
>> This fall I will be coring a variety of trees in tropical South America.
> I need to retrieve ring thicknesses since about 1970 (25-30 years).
> I would very much appreciate any tips about the length of the corer
> to cover this time span for "typical" trees.
>
I didn't think tropical (rain forest) trees even had rings. Not that
I've ever been there.